Process and an equipment for the plastic forming or shaping and simultaneous chip-free chopping of metal bars and wires

ABSTRACT

In a process and an apparatus for shearing metal bars under pressure, this bar is at the same time formed by cold flow and the pressure necessary for flowing is used for the purpose of the said shearing too.

United States Patent 1 Burany et a].

[ 1 PROCESS AND AN EQUIPMENT FOR THE PLASTIC FORMING OR SHAPING ANDSIMULTANEOUS CHIP-FREE CHOPPING OF METAL BARS AND WIRES [75] Inventors:Janos Biirany; Erno Csoy ak; Gabor Gulyas; Jozsef Nemeth; Ivan Vas;Andor Vollak; Jozsef Erdosi, all of Budapest, Hungary [73] Assignee:Gepipari Technologiai Intezet, Budapest, Hungary [22] Filed: Mar. 21,1972 [21] Appl. N0 236,762

Related US. Application Data [63] Continuation of Ser. No. 03,287, Jan.-16,- 1970,

abandoned.

[52] US. Cl. ..10/86 F, 72/332, 72/338 [51] Int. Cl ..B2ld 53/24, B2ld28/00 [451 Apr. 17, 1973 [58] Field of Search ..10/25, 27, 27.1, 10/72,76, 86, 86 F; 72/332, 334, 337, 338

[56] References Cited UNITED STATES PATENTS 756,141 3/1904 Renner .10/86F 1,619,495 3/1927 Wilcox .....10/27 PH 1,929,164 10/1933 Eden ..10/86 F2,077,519 4/1937 Prayer ..10/86 F 2,106,274 1/1938 Frayer et a1. ..10/86F 3,651,683 3/1972 Liebergeld ..l0/86 F Primary Examiner-Richard J.Herbst Assistant Examiner-E. M. Combs Attorney-Irvin S. Thompson [5 7]ABSTRACT In a process and an apparatus for shearing metal bars underpressure, this bar is at the same time formed by cold flow and thepressure necessary for flowing is used for the purpose of the saidshearing too.

2 Claims, 3 Drawing Figures PATENTEU APR 1 7 ma sum 2 [IF 2 PROCESS ANDAN EQUIPMENT FOR THE PLASTIC FORMING OR SHAPING AND SIMULTANEOUSCHIP-FREE CHOPPING OF METAL BARS AND WIRES This is a continuation, ofapplication Ser. No. 3,287, filed Jan. 16, 1970, now abandoned.

Various methods are known for the chip-free chopping of metal bars andwires by shearing and subsequent cold impact forming (plastic forming).It is the object of the present invention to improve such known methodsby subjecting the .workpiece simultaneously i.e. in the same step withthe chopping, to plastic formation, conveniently by means of flowing.

According to the invention this is performed with the aid of a mandrelwhich penetrates the interior of the metal bar or wire so as to producea hollow body.

It is another object of the invention to produce by the same methodcompact profiled bodies. A combination, i.e. simultaneous execution ofboth types of forming operations constitutes a further object of thepresent invention.

When hollow bodies are produced with the method according to theinvention, it becomes possible to manufacture punches disks, female nutsor the like articles, which up to now could only be manufactured bymachining or punching. These conventional manufacturing methods weretime consuming, and entailed large amounts of scrap. With the methodaccording to the invention, however, wherein the inner cavity is formedby flowing (cold impact forming), and this is combined with chopping,where the ambiance of the shorn surface of the workpiece is brought intoa condition of mechanical stress approximating the yield point, itbecomes possible to manufacture in a quick and cheap manner with noscrap, compact profiled bodies as well as hollow bodies, or profiledhollow bodies, such as for example the semi-finished products for femalenuts.

Thus the most important feature of the invention is the idea that thestress produced in the workpiece for plastic flowing is at the same timeutilized for a chipfree'chopping of the said workpiece by shearing undercompressive stress.

The invention is more particularly described below with reference to theaccompanying drawing showing two preferred embodiments of the equipmentserving to carry out the method according to the invention, in whichFIG. 1 is a schematic sectional view of the principal part of theequipment and FIGS. 2 and 3 represent another embodiment of theequipment in two different working phases, also schematically.

In FIG. 1 a bar 4 passes through the bore of a fixed tool 2, said borecoinciding in size and shape with the profile of the bar. A movable tool1 acts also as a die and has a bore coinciding in shape and size to thearticle to be produced, thus, the two bores are different in size aswell as profile. The movable tool 1 is also suitable for guiding amandrel 5, provided for cold flowing and the cavity of tool 1 servingthat purpose catches the external diameter and shape of the mandrel.

Feed blocks 3 serve to advance the bar 4. When feed has advanced so faras to reach the position shown in the figure, that is, when the bar 4bears on the cavity of the movable tool l,then the mandrel 5 carries outan opposed movement, i.e. it advances from right. to left according tothe drawing, and thus penetrates into the interior of the bar 4.Accordingly, shaping begins, and that portion of the metal bar 4 whichis now in the movable tool 1, fills up completely the cavity or bore ofsaid tool. After this step has been completed, that is, when the mandrelhas penetrated the bar so deeply as to fill up the cavity ofthe movabletool, this tool starts advancing, i.e. chopping by shearing begins, andis also completed in such a manner that the mandrel moves together withthe movable tool. 7

In order to achieve the process described above, it is obviouslynecessary that the device actuating the mandrel 5 also participates inthe movement carried out in order to achieve shearing. For this purposea hydraulic device may be employed to press the mandrel into the metalbar, said hydraulic device being connected with the source of thehydraulic fluid by means of flexible hoses. In this case nothingprevents the mandrel and its actuating mechanism from moving togetherwith the moving too]. Other embodiments can also be used, i.e. themandrel 5 may be connected with the moving or ac tuating means with theaid of a lever system whichpermits motion perpendicular to thelongitudinal axis. In another embodiment the extremity of the mandrel 5slides during shearing along the length of the means pushing oradvancing said mandrel.

The mandrel may have a circular or profiled cross section.

If it is intended to manufacture, for example, the semi-finished productrequired for producing female nuts, i.e. non-threaded female nuts from acompact, smooth bar of circular cross section, the cavity of the movabletool 1 will have a hexagonal cross sectionyso that when the mandrel 5penetrates, both the internal bore and the hexagonal outer circumferenceof the female nut are formed, and the :metal must have a mechanicalstress reaching at least the yield point. Then the chopping isperformed, i.e. the stress produced for shaping is according to theinvention, also employed for chopping by shearing. lf, however additional stress is required, it is possible to use the feed of the bar 4for increasing the stress by making the bar 4 bear on the tool 1.

If alternatively no mandrel is employed, the axial feed pressure can beselected to be so high as to achieve flowing and upsetting of the metalcontained in the die, so that it fills up the cavity. Compact profiledbodies may thus be produced. In this event too the main advantage of theinvention is utilized, i.e. the stress produced for flowing is employedfor chopping. ln other words, the stress brought about in the workpieceis used for a dualpurpose: plastic formation as well as chopping byshearing, without any scrap formation.

In the embodiment represented in FIGS. 2 and S the metal bar 4 is causedto bear upon the mandrel 5a with its conical extremity (FIG. 3). Themandrel acts also as an ejector means. During and/or after the feed themandrel is displaced towards the left side of the drawing, whereupon thesituation according to FIG. 2 is produced, i.e. both the cylindricalcavity in the movable tool and the conical cavity in the fixed tool 2are filled up by the metal to be formed. Thereafter the cylindrical partis separated by shearing, on the action of the movable tool.

Of course the widening end of bar 4 may have a shape other than conicaland the cross section of the part to be cut away may equally be otherthan cylindrical. In any case the advantage can be achieved that thediameter of the chopped-up product can be larger than that of thestarting metal bar. A further advantage resides in the fact that theconical surface between the starting metal bar and the workpiece to becut away offers a strong and reliable bearing surface against thepressure of the ejector mandrel 5a. In this manner greater stress can beproduced in the metal bar, for identical feeding or clamping forces.

A further significant advantage of the method according to the inventionis the elimination of difficulties due to the manufacturing inaccuracy(size tolerances) of the starting metal bar or wire, since thedimensions of the product upset in the cavity of the movable tool 1 arenot influenced by the size tolerances of the starting metal bar. Itfollows from this that products of nonstandard dimensions may be easilymanufactured from standard sized starting metal bars.

For achieving the above described advantages and for carrying out thedescribed operational steps, it is not essential, to give the startingmetal bar the conical shape according to FIGS. 2 and 3, but this conicalshape is always produced in the course of the process. So at thebeginning of the work the metal bar 4 may be cylindrical throughout,whereas in the course of producing the first chopped-off article atransitional portion is produced between the starting rod and thefinished product, this portion having a cross section increasing towardsthe chopped-off article.

We claim 1. A process for the plastic formation and chopping of metalbars and wires with a fixed and a movable shearing tool, comprisingintroducing a metal bar into a die comprised in part by said movabletool, said die having a fixed part that progressively enlarges in thedirection of said movable tool, pressing a mandrel against said metalbar thereby to subject a portion of the metal bar which is in the die toplastic deformation by flowing thus filling up the cavity of the die,and moving said movable tool and mandrel transverse to said fixed diepart thereby to shear from said bar an article having a cross sectionsubstantially larger than the starting metal bar while leaving on saidstarting metal bar in said fixed die part an end portion of saidstarting metal bar that enlarges toward the shear plane between saidarticle and said end portion of said starting metal bar.

2. A device for forming and cutting off workpieces from metal bars andwires, comprising a tool having a cavity therein of a size larger thanthe workpiece to be shaped, a mandrel movable in closely slidingrelationship with the sides of the cavity to upset an end of theworkpiece thereby to fill the cavity, the tool having a movable portiondefining a portion of said cavity whereby upon conjoint movement of saidmovable portion and said mandrel, a portion of the upset end of theworkpiece is sheared off, the mandrel being further movable to ejectsaid sheared-off portion of the workpiece, said portion of the cavitydefined by said movable portion of the tool being cylindrical, theremainder of t e cavity tapering from a great-est diameter adjacent saidcylindrical portion to a least diameter remote from said cylindricalportion.

1. A process for the plastic formation and chopping of metal bars and wires with a fixed and a movable shearing tool, comprising introducing a metal bar into a die comprised in part by said movable tool, said die having a fixed part that progressively enlarges in the direction of said movable tool, pressing a mandrel against said metal bar thereby to subject a portion of the metal bar which is in the die to plastic deformation by flowing thus filling up the cavity of the die, and moving said movable tool and mandrel transverse to said fixed die part thereby to shear from said bar an article having a cross section substantially larger than the starting metal bar while leaving on said starting metal bar in said fixed die part an end portion of said starting metal bar that enlarges toward the shear plane between said article and said end portion of said starting metal bar.
 2. A device for forming and cutting off workpieces from metal bars and wires, comprising a tool having a cavity therein of a size larger than the workpiece to be shaped, a mandrel movable in closely sliding relationship with the sides of the cavity to upset an end of the workpiece thereby to fill the cavity, the tool having a movable portion defining a portion of said cavity whereby upon conjoint movement of said movable portion and said mandrel, a portion of the upset end of the workpiece is sheared off, the mandrel being further movable to eject said sheared-off portion of the workpiece, said portion of the cavity defined by said movable portion of the tool being cylindrical, the remainder of the cavity tapering from a great-est diameter adjacent said cylindrical portion to a least diameter remote from said cylindrical portion. 